Sites periodically need to declare a downtime, either one scheduled in advance (maintenance, etc.), or in some cases in response to a critical outage (power, cooling, etc.). In the latter case the ability to declare the outage quickly is useful in terms of informing ATLAS about the problem. This can avoid a situation where the site is down, but if the outage has not yet been reported then the site may begin receiving problem tickets like GGUS.
US sites have two options for declaring downtimes: